The long-term objective is to develop a computer-aided prosthetic socket design to replace the current method of manual modification of a plaster cast.With the new system the external shape and the internal structural information of the residual limb would be acquired by an ultrasound scanning device, followed by a three dimensional (3-D) limb model construction, model modification, and socket design performed on a computer. Phase I would focus on the development of an ultrasound compound B-Scan imaging method optimized to maximize measurement accuracy and image quality, while minimizing data acquisition time and hardware complexity. Specific aims would attempt to: demonstrate that the external shape of a limb can be determined from ultrasound echo with an accuracy adequate to the practice of prosthetic socket design; demonstrate that the internal structural information of a limb, such as bone position, fat-muscle distribution can be distinguished by compound ultrasound B-scan images; and ascertain that it is technically feasible to engineer a relatively low-cost ultrasound scanner to acquire the required information at an acceptable speed. The results would be vital in the prototype design planned for the Phase II.